Q1 ) Can one who is reborn in ghost realm / deva realm recall his previous lives ?
Q2)In this life i practise Buddhism seriously but have not reached to the point to become arahant or enlightened .In my next time , if i reborn in the human or deva realm , will i have 100% opportunity to continue to practise Buddhism because i don't want to practise other religion except Buddhism .
Q1) If we were to use our present knowledge and experience in this existence, I would say there is a possibility. We know some people have this uncanny ability to remember past lives. Apart from that, I really don't know.
Q2) If we interprete the workings of the law of kamma, we would realize that certain kamma will produce certain results. If we want to associate with the Dhamma in our future lives, we have to practise the Dhamma seriously; and also spread the Dhamma. Remember, the highest merits are those actions relating to the dispensation of the Dhamma. You would also know that to be born in the deva realm means to "enjoy" a peaceful and happy existence as the fruits of good kamma. It is in the human realm that one has a greater chance to practise the Dhamma.